FUNCTIONAL CELL-SURFACE EXPRESSION OF BAND-3, THE HUMAN RED-BLOOD-CELL ANION-EXCHANGE PROTEIN (AE1), IN K562 ERYTHROLEUKEMIA-CELLS - BAND-3ENHANCES THE CELL-SURFACE REACTIVITY OF RH ANTIGENS

Human K562 erythroleukemia cells were transfected with human band 3 (a nion exchanger 1 [AE1]) cDNA, using the pBabe retroviral vector. Stabl e K562 clones expressing band 3 were isolated by flow cytometry, and s urface expression was quantified by immunoblotting. The function of ba nd 3 expressed at the cell surface was demonstrated in chloride transp ort assays. K562 cells expressing band 3 also displayed high levels of the Wr(b) blood group antigen, confirming the role of band 3 in Wr(b) expression, and an increase in the low levels of endogenous Rh antige n activity. We also performed coexpression experiments with K562 clone s that had previously been transduced with cDNAs encoding RhD or RhcE polypeptides. The transfection and expression of band 3 in these clone s substantially increased the levels of RhD and cE antigen activity ex pressed on the cells and also increased the reactivity of the cells wi th antibody to the endogenous Rh glycoprotein (RhGP, Rh50). The increa sed reactivity of Rh antigens may result from cell surface or intracel lular interactions of band 3 with the protein complex which contains t he Rh polypeptides and RhGP, or from indirect effects of band 3 on the membrane environment. This work establishes a system for cell surface expression of band 3 in a mammalian cell line, which will enable furt her studies of the protein and its interactions with other membrane co mponents. (C) 1998 by The American Society of Hematology.